首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 216 毫秒
1.
对第二类吸收热泵热管式降膜吸收器溶液降膜吸收传热传质并通过热管移出吸收热的过程进行了数值研究.根据所求得的波动膜流解及建立的数学模型,通过求解热管加热段外壁面溶液波动降膜传递方程和热管传热方程,研究了膜雷诺数、低位余热温度、输出热温度及降膜波动等因素对传热传质过程的影响,并与平滑膜进行了比较.  相似文献   

2.
构建了氨水降膜吸收实验设备,研究垂直管内降膜绝热吸收性能.通过套管换热器调节稀溶液入口过冷度,给予溶液吸收潜力,进行变工况降膜吸收实验.基于传质微分方程推导一种新的舍伍德数计算方法,用于传质性能评估.实验表明,传质速率以及舍伍德数随着雷诺数的增大而增大.增加吸收压力,稀溶液入口过冷度均能强化传质效果.具有过冷度的耦合传热传质过程传质速率及舍伍德数大于单独的过冷绝热吸收或者耦合传热传质吸收.利用实验结果拟合绝热吸收传质舍伍德数方程,可应用于传热传质分离的降膜吸收器热设计.
  相似文献   

3.
结合板式降膜技术与膜反转技术的优势,提出了一种新型膜反转板式降膜再生器.通过建立和求解其再生过程传热传质数学模型,得到液膜内的浓度、温度分布特征.揭示了再生过程蒸汽发生的特点,比较了不同倾斜角度、反转次数和分段位置的降膜板布置下再生过程的再生效果,确立了设计条件下一次反转的最佳膜反转板式降膜再生器结构.研究结果表明,膜反转板式降膜再生器比竖板降膜再生器更加高效紧凑.  相似文献   

4.
针对以溴化锂水溶液为工质的水平管吸收器,考虑润湿比、变膜厚和横向对流作用,建立了描述管表面的降膜流动和管间滴状吸收传热传质耦合过程的数学模型,采用涡量流函数法进行数学模型求解。根据数值计算结果,分析了溶液温度、浓度和吸收速率沿管排不同位置和水平管管间的变化,以及溶液喷淋密度和进口浓度对吸收器整体传热传质性能的影响。结果表明,提高喷淋密度可以改善吸收器传热性能,提高溶液进口浓度可改善传质性能,滴状吸收过程约占总吸收量的20%。与实验数据的对比说明建立的数学模型是合理的。  相似文献   

5.
针对增温型吸收热泵的一级装置,对热管外壁面装有轴向翅片的热管式降膜吸收器的降膜传热传质过程进行了数值研究,在假定壁温和翅片温度恒定及降膜厚度不变的基础上,对几组不同翅片高度和间距的情况进行了计算,结果表明,在离入口一定距离范围内,由于翅片的冷却作用而明显了降膜传热传质。  相似文献   

6.
针对以溴化锂水溶液为工质的水平管吸收器,考虑润湿比、变膜厚和横向对流作用,建立了描述管表面的降膜流动和管间滴状吸收传热传质耦合过程的数学模型,采用涡量一流函数法进行数学模型求解。根据数值计算结果,分析了溶液温度、浓度和吸收速率沿管排不同位置和水平管管问的变化,以及溶液喷淋密度和进口浓度对吸收器整体传热传质性能的影响。结果表明,提高喷淋密度可以改善吸收器传热性能,提高溶液进口浓度可改善传质性能,滴状吸收过程约占总吸收量的20%。与实验数据的对比说明建立的数学模型是合理的。  相似文献   

7.
溴化锂水溶液降膜吸收强化技术的实验研究   总被引:4,自引:0,他引:4  
在吸收式制冷技术中,提高溴化锂水溶液吸收蒸汽效率的手段主要是采用高效传热传质元件和添加表面活性介质。本文主要研究竖直平板流降膜吸收中添加表面活性介质的强化吸收技术。选择一种典型的表面活性介质;2-乙基-己醇,研究在一定实验工况下加入活性介质后不同降膜雷诺数Re、溶液进口温度ts,i、吸收压力、活性介质浓度以及不同降膜长度试件下的吸收强化。  相似文献   

8.
降膜式发生器的传热传质研究   总被引:6,自引:0,他引:6  
降膜式发生器在溴化锂吸收式制冷机与热泵中得到了一定的应用,溴化锂降膜式发生器在较小的液液量和较小的温差下获得较高的热流密度和传势传质系数,尤其是当液膜沿着水平管外作降膜流动时,传热传质效果更佳,为此建立了省化锂降膜式发生器溶液发生过程传南的数学模型,该模型考虑了流动、传势与传质同时进行相互耦合的特点,对不同布液方式下的液膜流动初速进行了修正,对模型进行求解,并建立了实验台对降膜式发生器的传热传质进行实验,通过对800多组数据进行回归得出了计算传热与传质的准则关系式。  相似文献   

9.
竖直矩形通道降膜吸收器热质性能的试验研究   总被引:1,自引:0,他引:1  
试验研究了溴化锂水溶液沿竖直矩形通道降膜吸收过程的传热传质情况。结果表明,溴化锂水溶液降膜流量、吸收压力、溶液进口浓度及进口温度对总传热系数、平均降膜吸收率的影响比较大。  相似文献   

10.
水平管降膜换热器具有热质传递效率高、阻力小、结构简单等优点,被广泛应用于化工等传统领域及能源利用的节能减排领域。降膜换热器内部发生复杂的流动及传热传质相互耦合过程。介绍了实验及模拟研究手段的进展,综述了不同操作参数(气体温度、流向及流量,溶液流量、温度及浓度,内部媒介流量及温度等)与结构参数(管径、管间距等)对水平管降膜管间流型、液膜厚度与润湿性等流动特性的影响规律,以及对蒸发传热特性、吸收传热传质特性等换热器性能的影响规律,包括整体性能和局部微细特征,为水平管降膜换热器的性能优化提供理论支撑。指出在不同气流特征以及多因素相互作用下多维度的局部流动与传热传质性能的耦合影响规律以及强化换热手段会是水平管降膜换热器未来研究的重点方向。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

15.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

16.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

17.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

18.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

19.
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.  相似文献   

20.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号